DABROWSKI ROMAN
TROKHIMETS DIMITRI
DZIADUSZEK JERZY
SASNOVSKI GENADI
LAPANIK VALERY
| WO1986005486A1 | 1986-09-25 | |||
| WO1986005484A1 | 1986-09-25 | |||
| WO1995004790A1 | 1995-02-16 |
| DE4227772A1 | 1994-02-24 |
PATENT ABSTRACTS OF JAPAN vol. 18, no. 122 (C - 1173) 28 February 1994 (1994-02-28)
| 1. | Liquid crystalline compounds represented by general formula 1 R1A1ZιA2Z2A3R2 1 in which R1 and R2 are the same or different and represent a terminal group Y(CH2)n(0)_(CH2)ιr(0)r(CH2)p or Y(CH2)nCH=CH(CH2)p, where Y is an H, F, or CI atom or a CN or OCF3 group, n, p and k assume values from 0 to 7, while m and I denote 0 or 1 ; Z, denotes a ring of the formula chosen from the set comprising formulae from 2 to 9, Z2 denotes a single bond or a ring chosen from the set comprising formulae from 2 to 9 and at the same time the position of cyclohexene rings Z and Z2 in relation to other neighboring rings is always such that their double bond is not conjugated with an aromatic ring; Y, in formulae 29 denotes a F, Cl atom or a CN, CH3, CH30, C2H5, C2HsO group; A, A2, A3 denote a single bond or a fragment from the set comprising formulae from 10 to 18, where X,, X2, X3 and X4 are independent and denote an H or F atom, while B and B, denote a single bond or a CH2CH2, CsC, CH=CH, OCH2, CH20 bridge group. |
| 2. | Liquid crystalline mixtures containing at least two compounds and at least one of them is a compound of general formula 1, R1A1Z1A2Z A3R2 1 in which R, and R2 are the same or different and represent a terminal group Y(CH2)n(0)m(CH2)k(0)r(CH2)p or Y(CH2)nCH=CH(CH2)p1 where Y is an H, F, or Cl atom or CN, OCF3 group, n, p and k assume values from 0 to 7, while m and I denote 0 or 1 ; Z1 denotes a ring of formula chosen from the set comprising formulae from 2 to 9, Z2 denotes a single bond or a ring chosen from the set comprising formulae from 2 to 9 and a position of cyclohexene rings Z1 and Z2 in relation to other neighboring rings is always such that their double bond is not conjugated with an aromatic ring; Y, in formulae 29 denotes a F, Cl atom or a CN, CH3, CH30, C2H5 or C2H50 group; A A2, A3 denote a single bond or the fragment of a formula from the set comprising formulae from 10 to 18, where X1f X2, X3 and X4 are independent and denote an H or F atom, while B and B1 denote a single bond or a CH2CH2, C=C, CH=CH, OCH2 or CH20 bridge group. |
| 3. | A display consisting of two parallel plates, at least one of which is made of transparent material, supporting the electrodes, aligning and/or isolating layers and/or colored filters, between which a liquid crystalline material is used, characterized by the fact that said liquid crystalline material is a mixture as descriebed in claim 2. SUBSTITUTE SHEET. |
The invention is applicable to information display technology and concerns liquid crystals which are laterally substituted derivatives of cyclohexane or cyclohexene, mixtures containing them and a liquid crystal display utilizing said mixtures.
Liquid crystal compounds containing a cyclohexane ring in their molecules, and to a lesser degree, those with a cyclohexene ring are utilized as components of mixtures applicable to different kinds of displays. This is due to their low viscosity and high chemical stability. The liquid crystalline materials of this type are disclosed in PL 147527, PL 137996, PL 153286, PL 153287, PL 138287, PL 157205, PL 15551, DE 2636684, DE 4111824, DE 4023107, DE 411998, DE 4018651 , DE 4035509, JP 91:220145, JP 91:246270, JP 91 :182190, EP 458176, GB 2253402, WO 91:10716.
Lately, because of the requirements of the active matrix technology and the STN-effect derivatives containing in the lateral and terminal position of their molecules a fluorine atom gain their importance. The proof of this are the following patent specifications: DE 4032579, DE 4030392, EP 460436, JP 92:255793. Fluorine containing compounds are characterized by high chemical stability. The introduction of fluorine or chlorine in the lateral position of the molecule causes the decrease of Δε ε ratio, what promotes the increase of the steepness of the electrooptical characteristic both in the TN and STN effects.
The following patent specifications disclose many compounds containing a fluorine atom or atoms in the lateral position of a benzene ring: DE 4106345, DE 4027315, DE 4034508, DE 4100288, DE 4010447, DE 4110018, DE 4016130, DE 4013297, DE 4108705, DE 4012764, DE 4107120, DE 4108398, DE 4013083, DE 4012403, DE 4107389, DE 4012014, DE 4111015, DE 4037519, DE 4113053, DE 4123539, DE 4111991 , DE 4104183, DE 4112024, GB 2240778, WO 92:05230, WO 91:05209, WO 92:06748, WO 91:12233, WO 91:15555, JP 91:203987, JP 92:54138, JP 93:58928, JP 92:91056, EP 492668, EP 502407, EP 507094.
Some substituted cyclohexanes are already known in the prior art. GB 2248059 dis¬ closes compounds substituted with fluorine. R. Eidenschink (Mol. Cryst. Liq. Cryst., 123, 57, (1985)) described compounds with a cyano group and DE 4111765 discloses compounds with a hydroxy group in 1 or 4 position of a cyclohexane ring. JP 92:13645, JP 92:13796 disclose a cyclohexanecarboxylic acid containing a -CF 3 substituent in the position 2 or 3; or 2 and 3. Patents JP 92:279244, JP 92:327548 and JP 93:58926 concern difluoro geminal cyclohexane derivatives. Patent application DE 4227772 describe also cyclohexene derivatives containing a perfluoroalkil group in position 1 and neighboring fluor atom in position 2 of cyclohexene ring.
The above mentioned compounds in spite of their diversity do not satisfy all require¬ ments connected with some new applications.
The present invention provides novel liquid crystalline compounds being the derivatives
of cyclohexane or cyclohexene represented by general formula 1 in which R, and R 2 are the same or different and represent a terminal group Y-(CH 2 ) n -(0) m -(CH 2 ) k -(0) r (CH 2 ) p - or Y-(CH 2 ) n -CH=CH-(CH 2 ) p -, where Y is an H, F, or Cl atom or a CN or OCF 3 group, n, p and k assume values from 0 to 7, while m and I denote 0 or 1 ; Z, denotes a ring of the formula chosen from the set comprising formulae from 2 to 9, Z 2 denotes a single bond or a ring chosen from the set comprising formulae from 2 to 9 and at the same time the position of cyclohexene rings Z 1 and Z 2 in relation to other neighboring rings is always such that their double bond is not conjugated with an aromatic ring; Y, in formulae 2 - 9 de¬ notes a F, Cl atom or a CN, CH 3 , CH 3 0, C 2 H 5 , C 2 H 5 0 group; A, A 2 , A 3 denote a single bond or a fragment from the set comprising formulae from 10 to 18, where X,, X 2 , X 3 and X 4 are inde¬ pendent and denote an H or F atom, while B and B 1 denote a single bond or a CH 2 -CH 2 , C≡C, CH=CH, OCH 2 , CH 2 0 bridge group.
The condition that the double bond of cyclohexene ring is not conjugated with π electron systems of neighboring aromatic rings makes that the compound 1 have high chemical and photochemical stability.
Liquid crystal compounds according to the present invention are being obtained by the transformation of 3,6-disubstituted cyclohex-2-en-1-ones, formula 21. Synthesis of these starting compounds is described in our concurrent application and it is shown in scheme 1. The manufacture process consists in heating acetoacetate acid ester of formula 19 with hydrochlo- ride of β-dimethylaminoethyl ketones (20) in the presence an alkaline hydroxide. Then cyclohex-2-en-1-one (formula 21) is transformed onto 2,5-disubstituted cyclohexan-1-one (formula 22) by the reduction with hydrogen in the presence of palladium catalyzer (advanta¬ geously 10% Pd/C).
The reduction is carried in alcohols or ethers advantageously in a mixture of isopropyl alcohol and dioxane (1:1). In the presence of a base, advantageously NaOH or KOH, 2,5- disubstituted cyclohexan-1-ones as the mixture of two isomers, with predominance of trans- isomer, is formed. The trans to cis ratio is 4:1 or higher. When this compound is prepared in an acid medium trans to cis isomer ratio is 2:1 or lower.
Since the methods for the preparation of 2,5-disubstituted cyclohexan-1-ones are based on 1,4-disubstituted cyclohex-1-enes, which are hydroborated with LiBH 4 and BF 3 Et 2 0, then oxidized with a solution of sodium dichromate and H 2 S0 4 , but this method was found to be less effective because due to the opening of cyclohexene ring too large amounts of byproducts originate (M.Hird et al., J.Chem.Soc.Perkin Trans., 2, 2337 (1993)).
2,5-Disubstituted cyclohexan-1-ones are transformed into compounds being the subject of the present invention as shown in scheme 2 and 3. The mixture of cis and trans isomers of compounds 22 may sometimes be used but in some cases the use of cis or trans isomers is
SUBSTITUTE SHEET
preferable. It will be explain later.
In schemes the following notation is used. The formulae of compounds derived from general formula 1 are denoted to indicate the kind of the lateral substituent (Y,=F, CN, Cl, CH 3 , C 2 H 5 0 are indicated by small characters a, b, c, d, or e respectively) and a kind of fragment Z 1 (when Z 1 is of formula 2, 9 or 5 numbers 1 , 2 or 3 are used respectively).
Fluorosubstituted compounds of formulae 1a1 and 1a2 (scheme 2) are obtained by heating ketone of formula 22 with diethylaminosulphur trifluoride in a solvent such as methy¬ lene chloride or benzene and the resulting difluoroderivative of formula 23 (scheme 2) is treated with a base, advantageously KOH or with alcoholate, advantageously sodium or potassium tert-butylate. isomeric compounds 1a1 and 1a2 are separated by crystallization or they are used in a form of the isomeric mixtures.
Compound of formulae 1b1 and 1b2 (scheme 2) are obtained from ketone 22 by treating it with acetone cyanohydrin in the presence of tertiary amines or alkaline metals carbonates in a solvent such as dioxane or tetrahydrofurane and resulting compound 24 is treated with POCI 3 in the presence of a tertiary aliphatic amine or pyridine. Isomeric com¬ pounds 1b1 and 1b2 are separated by crystallization or used in a form of the isomeric mixtures.
The chlorine substituted compounds (formulae 1c1 and 1c2 in scheme 2) are obtained by heating ketone of formula 22 with PCI 5 , PCI 3 or POCI 3 in a hydrocarbon or chlorocarbon, advantageously in hexane or benzene. The resulting intermediate of 25, without separation, is heated with water-alcohol solution of a base (advantageously NaOH or KOH). Isomeric com¬ pounds 1 d and 1 c2 are separated by crystallization or used in a form of the isomeric mixtures.
Compound of formulae 1d1 and 1d2 (scheme 2) are obtained from ketone 22 by treating it with a Grignard reagent (for example CH 3 Mgl) in anhydrous ethereal solution, then the product 26 is heated in the presence of catalytic amount of acids, advantageously p- toluenesulfonic, in toluene solution. Isomeric compounds 1d1 and 1d2 are separated by crystallization or used in a form of the isomeric mixtures.
Compounds of formulae 1e1 and 1e2 (scheme 2) are obtained by treating ketone 22 with triethyl ortoformate in the presence of p-toluenesulfonic acid in an alcohol, advantageously in ethanol.
The ratio in which constitutional isomers 1a1 and 1a2 or 1b1 and 1b2 or 1c1 and c2 or 1d1 and 1d2 or 1e1 and 1e2 are formed may be changed from 0 to 1 and it depends on the character of substituent in the compounds of formulae 23-26, conditions of the reaction, the temperature and a solvent and base used. These constitutional isomers may be separated into pure forms by crystallization. It is not always necessary and not always an optimal way be¬ cause the yield of the product is decreased when the crystallization procedure is repeated.
For formulation of liquid crystalline mixtures for display application instead of individual constitutional isomers 1a1 and 1a2 and so on the mixture of isomers may be used. The fixed
SUBSTITUTE SHEET
composition of the isomeric compounds may be obtained easily by mixing isomeric mixtures of different composition.
The compounds 1a2, 1b2, 1c2, 1d2, 1e2 exist in a form of cis and trans isomers, and only the trans isomer exhibits liquid-crystalline properties and is much less soluble. The second constitutional isomers 1a1, 1b1, 1c1 , 1d1, 1e1 exist only in one geometric form. This fact enables the separation of constitutional isomer 1a1 or 1b1 , 1c1 , 1d1 , 1e1 from its constitutional isomer 1a2 or 1b2 and so on.
To obtain the compounds of formulae 1a1 , 1b1, 1c1 , 1d1 or 1e1 in a pure state (sepa¬ rated from their constitutional isomers) a cis isomer of 2,5-disubstituted cyclohexan-1-one of formula 22 is used as a substrate. Then according to the reaction shown in scheme 2 com¬ pound 1a1 or similar and cis isomer of compound 1a2 or similar are formed only. Such a mixture of isomers is easily separated by crystallization, because the difference in solubility of the constitutional isomers is high. When the trans isomer of formula 1a2 or similar ones is needed, the use of trans isomer of 2,5-disubstituted cyclohexan-1-one is recommended.
The mixture of constitutional isomers 1a1 and 1a2 or 1a3 and similar ones may be used for the preparation of compounds with cyclohexane ring of the formulae 1a, 1b, 1c, 1d, 1e being subject of this invention. This is done by the reduction of the mentioned mixture of isomers with hydrogen in presence of the catalyzer (palladium on carbon in concentration 5 to 10%) as it is shown in scheme 3. Lateral group Y, is located in cyclohexane ring both in an axial and equatorial position.
Other methods for the preparation of cyclohexane derivatives are shown in scheme 4. Compound of formula 22 is reduced by treatment with sodium borohydride, then the resulting hydroxy derivative of formula 27 is treated with PCI 5 , SOCI 2 or PCI 3 and compound 1c is formed (scheme 4).
The compound of formula 1a (scheme 4) is obtained by the reduction of the compound of formula 22 with sodium borohydride and the treatment of the resulting hydroxy derivative 27 with diethylaminosulphur trifluoride (DAST) in a low-boiling solvent, advantageously in methy¬ lene chloride, at temperature below 20°C.
The method for the preparation of the constitutional cyclohexene isomers 1a3, 1b3, 1c3 is shown in scheme 5. 3,6-Disubstituted cyclohex-2-en-1-one is reduced by aluminium isopropylate to the unsaturated alcohol of formula 28 and then it is treated with diethylaminos¬ ulphur trifluoride in low-boiling solvent, advantageously in methylene chloride, at temperature below 0°C and compound 1a3 is obtained. For the preparation of compound 1b3 the alcohol of formula 28 is treated with methane sulfonyl chloride or toluene sulfonyl chloride and then the obtained sulphonic acid ester of formula 29 is treated with KCN in an alcohol solution.
The sulphonic acid ester of formula 29 treated with NaCI in an alcohol solution is converted into chlorine derivatives of formula 1c3.
SUBSTITUTE SHEET
Using the above mentioned methods one can easily obtain cyclohexane and cyclohex¬ ene derivatives which until now were difficult to obtain and to investigate. Many of the com¬ pounds according to the present invention show better parameters for some application than compounds know in the prior art.
The formulae from 1.1 to 1.109 wherin R, and R 2 are alkil chain containing up to 8 carbon atoms show the compounds having the advantageous properties. Y,=F is preferred in structures with two, three, four and five rings, and Y,=CI, CN, CH 3 , 0CH 3 is recommended for structures with four and five rings.
Liquid crystal compounds according to the present invention, especially compounds of formula 1.1-1.109, make it possible to create mixtures with low conductivity and different values of an optical anisotropy (Δn) and of the ratio Δε/ε x . When these compounds contain the cyclohexane or cyclohexene rings then liquid crystal mixtures containing them have low values of Δn and can be used for liquid crystal displays working in the condition of the first transmis¬ sion minimum (Δnd = 0,5^ -0,48 forλ=589). When these compounds in their molecules contain benzene rings, especially when these rings follow one another (biphenyl moiety) then liquid crystal mixtures containing them have higher values of Δn. Mixtures with high values of an optical anisotropy can be used in setups utilizing the condition of second and further transi¬ tion minima and also in PDLC displays, in which the liquid crystal mixture is dispersed in polymers.
The lateral substituents control the value of Δε ε x ratio and by proper selection of mixture components from the compounds according to the present invention one influences the value of Δε/ε ratio in mixtures and in this way controls the steepness of the electrooptical characteristic of a display (the dependence of light transmission upon the voltage at the display electrodes).
The object of the invention are also liquid crystalline mixtures containing at least two compounds, at least one of them is a compound of general formula 1,
Rι-A -Z 1 -A 2 -Z 2 -A 3 -R 2 1 in which R, and R 2 are the same or different and represent a terminal group Y-(CH 2 ) n -(O) m -(CH 2 ) fc -(0) r (CH 2 ) p - or Y-(CH 2 ) n -CH=CH-(CH 2 ) p -, where Y is an H, F, or Cl atom or CN, OCF 3 group, n, p and k assume values from 0 to 7, while m and I denote 0 or 1; Z, denotes a ring of formula chosen from the set comprising formulae from 2 to 9, Z 2 denotes a single bond or a ring chosen from the set comprising formulae from 2 to 9 and a position of cyclohex¬ ene rings Z 1 and Z 2 in relation to other neighboring rings is always such that their double bond is not conjugated with an aromatic ring; Y 1 in formulae 2-9 denotes a F, Cl atom or a CN, CH 3 , CH 3 0, C 2 H 5 or C 2 H 5 0 group; A, A 2 , A 3 denote a single bond or the fragment of a formula from the set comprising formulae from 10 to 18, where X,, X 2 , X 3 and X 4 are independent and denote
SUBSTITUTE SHEET
an H or F atom, while B and B, denote a single bond or a CH 2 -CH 2 , C≡C, CH=CH, OCH 2 or CH 2 0 bridge group.
Compounds of formulae from 1.1 to 1.109 are examples of compounds with advanta¬ geous features for preparing mixtures.
Mixtures according to the invention contain exclusively compounds of formula 1 or compounds 1 together with other known liquid crystalline compounds and/or nonliquid crystal¬ line compounds such as solvents and/or optically active compounds and/or dichroic dyes and/or polymers.
The mixtures containing two- and three-ring compounds which are the object of the invention show low or intermediate clearing temperatures. The presence of four-ring or five-ring compounds of the present invention, advantageously compounds of formulae 1.38+1.67 and 1 76÷1.94 in mixtures, causes that the mesophase range of nematic mixture may be broader than 150°C.
The mixtures according to the present invention are useful for an active matrix because they are characterized by high resistivity (>10 13 Ω-cm), a broad range of nematic phase, short switching times and high contrast. These mixtures are useful for displays working at the first transmission minimum and allow to obtain good contrast in a broad range of view angle. They have also excellent steepness in STN mode. High chemical stability and resistivity of these mixtures enables keeping electrical parameters determining the performance of a display to be stable.
The present invention relates also to a display consisting of two parallel plates, at least one of which is made of transparent material, supporting the electrodes, aligning and/or isolat¬ ing layers and/or colored filters, between which the liquid crystalline according to the present invention is used.
The examples presented below illustrate the invention without, however, limiting the same.
Example 1
2-Butyl-5-(4-ethoxyphenylethyl-2)cyclohexan-1-one
0.1 mol of 3-(4-ethoxystyryl)-6-butylcyclohex-2-en-1-one and 30 g of KOH was dissolved in 150 ml isopropanol and hydrogenated with gaseous hydrogen at 50°C in the presence of 1 g of catalyzer (10% Pd/C) until hydrogen was not absorbed any longer. Then the catalyzer was filtrated off and the solvent was evaporated. The residue was poured into water and extracted with hexane. After hexane was evaporated the residue was several times recrystallized from ethanol, whereupon 13 g (43%) of 2-trans-butyl-5-(4-ethoxyphenylethyl-2)cyclohexan-1-one
SUBSTITUTE SHEET
having the following phase transition temperatures Cr 57 (N 20) I was obtained.
The liquors were collected and then refluxed with active carbon (10 g). After filtration of the solution the alcohol was partially evaporated. The concentrated solution was cooled and a mixture cis and trans isomers in ratio 1 :5 (5 g) was obtained. The residual oil after evaporation of the liquor (10 g) contains cis isomer of purity 95%.
In an analogues way the trans isomers of the following compounds were separated off in a pure state:
2-trans-pentyl-5(4-ethoxyphenylethyl-2)cyclohexan-1-one, Cr 66.5 I; 2-trans-propyl-5-(4-pentylbiphenyl-4'-yl)cyclohexan-1-one, Cr 103 S B 155 I; 2-trans-methoxy-5-(4-pentylbiphenyl-4'-yl)cyclohexan-1-one, Cr 128 S B 184 I; 2-trans-pentyl-5-(4-(trans-4-propylcyclohexyl)phenyl)cyclohe xan-1-one, Cr 99 S B 142.5 N 151.5 1;
2-trans-pentyl-5-(4-methoxyphenylethyl-2)cyclohexan-1-one , Cr 72.5 I; 2-trans-(trans-4-butylcyclohexylethyl-2)-5-(3,4-difluorophen yl)cyclohexan-1-one, Cr 89 (N 88.5) l;
2-trans-(trans-4-butylcyclohexylethyl-2)-5-(4-(trans-4-pr opylcyclohexyl)phenyl)cyclohexan-1- one, Cr 134.5 S x 178 S A 248 N 253 I;
2-trans-pentyl-5-(trans-4-phenylcyclohexyl)cyclohexan-1-o ne, Cr 69.5 N 103 I; 2-trans-propyl-5-(4-(trans-4-propylcyclohexyl)phenyl)cyclohe xan-1-one, Cr 139 (N 137) I; 2-trans-pentyl-5-(4-(trans-4-propylcyclohexyl)phenyl)cyclohe xan-1-one, Cr 44 S B 147.5 N 164 1;
2-trans-(trans-4-butylcyclohexylethyl-2)-5-(trans-4-pheny lcyclohexyl)cyclohexan-1-one, Cr 61 S x 229 l.
Example 2
Synthesis of 1-pentyl-2-cyano-4-(4-(trans-4-propylcyclohexyl)phenyl)cyclo hex-1-ene
A mixture of 2-cis-pentyl-5-(4-(trans-4-propylcyclohexyl)phenyl)cyclohexa n-1-one (0.05 mol), acetone cyanohydrin (0.2 mol), triethylamine (0.2 mol) and 40 cm 3 of tetrahydrofurane was left for 24 h at room temperature. After the addition of 100 cm 3 of benzene the mixture was diluted with water. The layers were separated and the benzene layer was washed, sequentially, with water and diluted hydrochloric acid and dried over anhydrous sodium sulfate. Thereafter mixture was filtrated and benzene was evaporated. To the residue 4 cm 3 of pyridine and POCI 3 (0.06 mol) was added and the resulting mixture was heated while boiling for 7 hours. Then the mixture was poured into water with ice and the product was extracted into benzene. The benzene extract was washed with water and with diluted hydrochloric acid, dried over MgSO„
SUBSTITUTE SHEET
and filtrated. After the evaporation of benzene the residue was crystallized from methanol - isopropanol mixture to obtain a solid which melted at 50.5°C. Mass spectrum: 377 (M * ), 253, 228, 130, 91, 69, 41, 28.
Example 3
Synthesis of 1-cyano-3-trans-(4-(trans-4-propylcyclohexyl)phenyl)-6-penty lcyclohex-1-ene
A mixture containing 2-trans-pentyl-5-(4-(trans-4-propylcyclohexyl)phenyl)cyclohe xan-1-one (18.3 g, 0.05 mol), acetone cyanohydrin (7.2 g, 0.085 mol), 8.5 cm 3 triethylamine and 80 cm 3 of tetrahydrofurane was left for 24 hours. Thereafter the mixture was diluted with water and benzene was added. After the separation the benzene layer was washed with water, then with diluted hydrochloric acid and dried over MgS0 4 . After the evaporation of benzene the product was crystallized from methanol to obtain 15 g of the crystalline compound which melted at 130°C. This compound was dissolved in 90 cm 3 of pyridine and after the addition of 15 cm 3 of POCI 3 the resulting mixture was left for 48 hours. Thereafter the mixture was poured into water with ice and extracted with benzene. After the separation the benzene layer was washed with water and with diluted hydrochloric acid and then dried over MgS0 4 and filtrated. The residue left after the evaporation of benzene was recrystallized from methanol-isopropanol mixture to obtain a mixture of isomers in ratio: 1-cyano-3-trans-(4-(trans-4-propylcyclohexyl)phenyl)-6- pentylcyclohex-1-ene 32% and 1-pentyl-2-cyano-4-(4-(trans-4-propylcyclohexyl)phenyl)- cyclohex-1-ene 68%. The subsequent recrystallizations led to the enrichment of the product with the first isomer and after several crystallizations it was possible to isolate it in a pure state (99.5%). The yield was 10.5%; m.p 37.5°C. Mass spectrum: 377 (M * ), 339, 253, 194, 182, 91 , 69, 28.
The liquors were joined and the residue left after the evaporation of the solvent was used as a starting material for the synthesis of cyclohexane derivatives.
Example 4
Synthesis of 1 -pentyl-2-cyano-4-trans-(4-(trans-4-propylcyclohexyl)phenyl) cyclohexane
The mixture of isomers (0.05 mol) obtained as described in example 3 was dissolved in a tetrahydrofurane-isopropanol (10:1) mixture. To the resulting mixture 0.2 g of Pd/C (10%) was added and connected to the source of hydrogen. The mixture was stirred until hydrogen was no longer absorbed. After that the catalyzer was filtrated off and the solvents distilled off and the product was crystallized from methanol-isopropanol mixture. The phase transition of the
SUBSTITUTE SHEET
obtained compound were Cr 57 (N 24) I.
Mass spectrum: 379 (M + ), 336, 281 , 229, 201 , 117, 91, 69, 41, 28.
Example 5
1-(trans-4-Butylcyclohexylethyl-2)-2-cyano-4-(4-(trans-4- propylcyclohexyl)phenyl)-cyclohex-1- ene (a) and 1-cyano-3-trans-(4-(trans-4-propylcyclohexyl)phenyl)-6-(tran s-4-butylcyclohexyl- ethyl-2)cyclohex-1-ene (b) were obtained in a similar way as described in example 3 starting from 2-trans-(trans-4-butylcyclohexylethyl-2)-5-(4-(trans-4-propy lcyclohexyl)phenyl)cyclohexan- 1-one. After the first crystallization the isomer ratio was a:b=68:32. The product obtained after the third crystallization was characterized by isomer ratio a:b=18:82 and the following phase transition temperatures Cr 94 (S A 74) N 144 I.
Example 6
1-Pentyl-2-chloro-4-(4-(trans-4-propylcyclohexyl)phenyl)c yclohex-1-ene
A mixture of 2-cis-pentyl-5-(4-(trans-4-propylcyclohexyl)phenyl)cyclohexa n-1-one (0.05 mol), PCI 5 (0.1 mol) and 100 cm 3 of benzene was heated while boiling and after cooling it was treated with 10% solution of KOH. Thereafter the organic layer was separated, washed with water, dried over anhydrous MgS0 4 and filtrated through a layer of Al 2 0 3 . After the evaporation of the solvent the oily liquid was crystallized from the methanol-isopropanol mixture to obtain a compound with the following phase transition temperatures Cr 57 (N 24) I, 99% pure with the yield 48%. Mass spectrum 388 and 386 (M * ), 228, 143, 130, 91, 41.
Example 7
1-(trans-4-Pentylcyclohexylethyl-2)-2-chloro-4-(4-(trans- 4-propylcyclohexyl)phenyl)cyclohex-1- en (a) and 1-chloro-3-trans-(4-(trans-4-propylcyclohexyl)phenyl)-6-(tra ns-4-butylcyclohexyl- ethyl-2)cyclohex-1-en (b) were obtained in a similar way as described in example 6 staring from 2-trans-(trans-4-butylcyclohexylethyl-2)-5-(4-(trans-4-propy lcyclohexyl)phenyl)cyclohexan-1- one. After the first crystallization the isomer ratio was a:b=61:39. The product obtained after the third crystallization was characterized by isomer ratio a:b= 68:32 and the following phase transition temperatures Cr 47.5 N 158.5 I. Mass spectrum compound (a): 484 and 482 (M * ), 330, 332, 228, 130, 69;
SUBSTITUTE SHEET
compound (b): 484 and 482 (M * ), 447, 357, 315, 267, 169, 125, 69.
Example 8
1-Hexyl-2-methyl-4-(4-(trans-4-pentylcyclohexyl)phenyl)cy clohex-1-en
To the Grignard reagent prepared from 0.1 mol of methyl iodide, 0.1 mol of magnesium chips and 200 cm 3 of diethyl ether the ethereal solution of (0.1 mol ) 2-hexyl-5-(4-(trans-4-pentyl- cyclohexyl)phenyl)cyclohexan-1-one was added and stirred for 4 hours. The resulting magne¬ sium salt was decomposed with 20% solution of H 2 S0 4 and the organic layer was separated and dried over Na 2 S0 4 . Then the solvent was evaporated and 50 cm 3 of toluene and catalytic amount of toluene-4-sulphonic acid were added to the residue and heated using azeotropic head until water stopped to evolve. Then the mixture was cooled and diluted with water. The toluene layer was separated, dried over Na 2 S0 4 and filtrated. The residue was dissolved in hexane, and the crude product was purified by column chromatography (Al 2 0 3 ) and recrystal- lized from isopropyl alcohol to obtain 28 g (70 %) of pure compound having the following phase transition temperatures Cr 3.5 S E 48.0 S B 52.5 I.
Example 9
1-Pentyl-2-ethoxy-4-(4-ethoxyphenylethyl-2)cyclohex-1-ene
A mixture containing 2-cis-pentyl-5-(4-ethoxyphenylethyl-2)cyclohexan-1-one (0.005 mol), ethyl ester of ortoformic acid (0.015 mol), catalytic amounts of p-toluenesulfonic acid and 150 cm 3 ethyl alcohol was stirred for 6 h. Thereafter it was diluted with water and extracted with ben¬ zene. After separating the benzene layer was washed with water and dried with Na 2 S0 4 . The oily residue left after distilling off benzene was dissolved in hexane and eluted on a column filled with silica gel collecting the fractions. On the basis of chromatographic analysis the fractions containing pure product were joined, the solvent was evaporated, 7.8 g (48 %) of oily liquid was obtained.
Example 10
1-trans-Pentyl-2,2-difluoro-4-(4-ethoxyphenylethyl-2)cycl ohexan
A mixture containing (0.01 mol) 2-trans-pentyl-5-(4-ethoxyphenylethyl-2)cyclo-hexan-1-one,
SUBSTITUTE SHEET
(0.01 mol) diethylaminosulphur trifluoride (DAST) and 15 ml benzene was heated while boiling for 24 hours. Thereafter the mixture was poured into water, the benzene layer was separated, washed with water, dried with MgS0 4 and filtrated. The crude product remained after the evaporation of the solvent was recrystallized from isopropanol. 2 g (60 %) of the compound having the following phase transition temperatures: Cr 34 (N 13) I was obtained. In the same way the following compounds were obtained: 1-trans-butyl-2,2-difluoro-4-(4-ethoxyphenylethyl-2)cyclohex ane, Cr 37.1 (N -8) I; 1-trans-pentyl-2,2-difluoro-4-(4-(trans-4-pentylcyclohexyl)p henyl)cyclohexane, Cr 66 S B 97 108.5 1; 1-propyl-2,2-difluoro-4-(biphenyl-4-yl)cyclohexan.
Example 11
1-Propyl-2-fluoro-4-(biphenyl-4-yl)cyclohex-1-ene
A mixture of 1-pentyl-2,2-difluoro-4-(biphenyl-4-yl)cyclohexane (0.05 mol), 45 cm 3 of ethylene glycol and KOH (0.05 mol) was stirred at 100°C for 7 hours, thereafter it was diluted with water and extracted with benzene. The benzene layer was washed with water, dried with MgS0 4 , filtrated. The residue left after the evaporation of the solvent was recrystallized from isopropa¬ nol, and 12.1 g (79 %) of the compound having the following phase transition temperatures Cr 81 N 87 I was obtained.
Example 12
2-trans-Pentyl-5-(4-(trans-4-propylcyclohexyl)phenyl)cycl ohexan-1-ol
The mixture of 2-trans-pentyl-5-(4-(trans-4-propylcyclohexyl)phenyl)cyclohe xan-1-one (0.05 mol), sodium borohydride (0.05 mol) and isopropyl alcohol (100 cm 3 ) was stirred and heated at temp. 50-60°C for 8 hours. After that the reaction mixture was acidified with hydrochloric acid solution and the organic layer was extracted into ether and the ethereal extract was washed successively with water and then dried (MgS0 4 ). The solvent was removed in vacuo and the crude product was recrystallized from hexane to obtain 16.6 g (90%) of the compound; m.p.
162°C;
Mass spectrum: 370 (M + ), 352, 281 , 228, 130, 117, 91, 69.
In the same way 2-trans-pentyl-5-(4'-propylbiphenyl-4-yl)cyclohexan-1-ol was obtained.
Mass spectrum: 364 (M * ), 307, 279, 237, 193, 180, 152, 91.
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Example 13
1-trans-Pentyl-2-fluoro-4-(4-(trans-4-propylcyclohexyl)ph enyl)cyclohexane
(0.01 mol) of (C 2 H 5 ) 2 SF 3 was added dropwise to (0.01 mol) 2-trans-pentyl-5-(4-(trans-4-propyl- cyclohexyl)phenyl)cyclohexan-1-ol which was previously dissolved in 15 cm 3 of CH 2 CI 2 , and cooled down to -78°C. Thereafter the cooling was stopped and the mixture was allowed to warm to room temperature, poured into water and the layers were separated. The organic layer was dried with Na 2 S0 4 , filtrated. After the evaporation of the solvent the crude product was recrystallized from ethanol. 2.4 g (65%) of the compound having the following phase transition temperatures: Cr 45 S B 135 N 140 I was obtained. Mass spectrum: 372 (M * ), 274, 228, 201 , 130, 117, 91 , 69.
Example 14
Mixture A of the following composition: wt %
4-(trans-4 -propylcyclohexyQbenzeneisothiocyanate 40
4-(trans-4 -hexylcyclohexyl)benzeneisothiocyanate 42
4-(trans-4-octylcyclohexyl)benzeneisothiocyanate 18 is characterized by the following parameters:
' N-l 42°C
V 10 /20°C 1.69V
V 5 o/20°C 1.95V
V 9 o/20°C 2.38V
Δn/20°C 0.168 η/20°C 12.9 mPa -s
Mixture B of the following composition: wt % mixture A 90
1 -(trans-4-butylcyclohexylethyl-2)-2-chloro-4-(4-(trans-4-pro pylcyclohexyl)phenyl)cyclohex-1 -en 7 1-chloro-3-trans-(4-(trans-4-propylcyclohexyl)phenyl)-6-(tra ns-
4-butylcyclohexylethyl-2)cyclohex-1-en 3 is characterized by the following parameters: T N ., 50°C
V 10 /20°C 1.65 V
V 5 o 20°C 1.91 V
V 9 o 20°C 2.35 V
SUBSTITUTE SHEET
η/20°C 17.5 mPa-s
Mixture C of the following composition: wt % mixture A 90
1-(trans-4-butylcyclohexylethyl-2)-2-cyano-4-(4-(trans-4- propylcyclohexyl)phenyl)- cyclohex-1-en 2
1-cyano-3-trans-(4-(trans-4-propylcyclohexyl)phenyl)cyclo hex-1-en 8 is characterized by the following parameters:
V 10 /20°C 1.70 V
V 5 o/20 0 C 1.95 V
V α 20°C 2.38 V η/20°C 19.4 mPa s
Example 15
Mixture D of the following composition was prepared wt %
4-(trans-4-propylcyclohexyl)benzeneisothiocyanate 35.0
4-(trans-4-pentylcyclohexyl)benzeneisothiocyanate 9.0
4-(trans-4-heptylcyclohexyl)benzeneisothiocyanate 16.0
4-methoxyphenyl-4-trans-pentylcyclohexanecarboxylate 10.0
4-(trans-4-ethylcyclohexyl)nonylbenzene 5.0
1-(4-(trans-4-ethylcyclohexyl)phenyl)-2-(trans-4-propylcy clohexyl)ethane 25.0 and then mixture E was prepared by using in the same amount 1-trans-pentyl-2-fluoro-4-(4-
(trans-4-propylcyclohexyl)phenyl)cyclohexane in mixture D instead of 1-(4-(trans-4-ethylcyclo- hexyl)phenyl)-2-(trans-4-propylcyclohexyl)ethane.
The following results were obtained in the STN-240 cell
Example 16
Mixture F of the following composition was prepared: wt %
4-(trans-4-pentylcyclohexyl)fluorobenzene 11.25
1-(trans-4-pentylcyclohexyl)-2-(4-fluorophenyl)ethane 28.85
1 ,2-(trans-4-propylcyclohexyl)ethane 2.2
1 ,2-(trans-4-pentyl)cyclohexyl)ethane 2.2
1-(4-(trans-4-ethylcyclohexyf)phenyl)-2-(trans-4-propylcy clohexyl)ethane 9.5
1-(4-(trans-4-pentylcyclohexyl)phenyl)-2-(trans-4-propylc yclohexyl)ethane 9.0
4-(trans-4-propylcyclohexyl)-1-(4-trans-(4-fluorophenyl)c yclohexylethyl-2)- benzene 4.4
4-(trans-4-butylcyclohexyl)-1-(4-trans-(4-fluorophenyl)cy clohexylethyl-2)- benzene 4.4
4-(trans-4-propylcyclohexyl)-1-ethoxybenzene 7.5
1 -(4-propylbicyclo[2,2,2]octyl)-2-(4-fluorobiphenyl-4 , -yt)ethane 2.75
1-(4-pentylbicyclo[2,2,2]octyl)-2-(4-fluorobiphenyl-4'-y ethane 8.7
1-(4-hexylbicyclo[2,2,2]octyl)-2-(4-fluorobiphenyl-4'-yl) ethane 9.25 and then mixture G was prepared by using in the same amount 1-trans-pentyl-2-fluoro-4-(4-
(trans-4-propylcyclohexyl)phenyl)cyclohexane instead of 1-(4-(trans-4-ethylohexyl)phenyl)-2-
(trans-4-propylcyclohexyl)ethane.
Both mixtures have resistivity higher than 5 -10 13 Ω cm and following results were obtained in
TN cell.
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